Mont Belvieu, TX has a population of 4,892 and is the 6,571st largest city in the United States. The population density is 305 per sq mi which is 214% higher than the Texas average and 236% higher than the national average. The median age in Mont Belvieu is 45 which is approximately 32% higher than the Texas average of 34. In Mont Belvieu, 68% of the population over 15 years of age are married, 89% speak English and 6% speak Spanish. 71% of Mont Belvieu residents were born in Texas, 23% were born out of state, 0% were born outside of the United States and 6% were foreign born.